It's not even close ... if Conor McGregor fights Floyd Mayweather, Muhammad Ali would've rooted for the IRISHMAN ... so says the champ's ex-wife.
"Ali don't like anybody dull, he likes everybody EXCITING," Khalilah Ali told TMZ Sports ... "He’d be a Conor McGregor [fan]. Conor McGregor's the guy."
Khalilah was married to Muhammad from '67 to '76 and has 4 children with the boxing legend.
Of course, Muhammad saw Mayweather fight ... but famously rooted for Pacquiao when they squared off in 2015.
As for McGregor ... he's gonna LOVE this video. He's praised Ali as one of his personal heroes and has said he's without a doubt the greatest fighter of all time.